The UAE (United Arab Emirates) is buying two more Erieye AEW (airborne early warning) aircraft from Sweden for $635 million each. These are the improved and enlarged versions of the two Swedish Erieye AEW aircraft the UAE bought in 2009. Those were based on the 13 ton Saab 340 airliner
h a cruising speed of 290 kilometers an hour and able to stay in the air about five hours per sortie. The radar can also spot ships at sea, and thus can also fill in for maritime reconnaissance. The latest version of Erieye is carried in the Global 6000, a 42 ton twin-jet aircraft with a cruising speed of 900 kilometers an hour and an endurance of about ten hours.
The Erieye system is built around an Active Electronically Scanned Array (AESA) radar (which consists of thousands of tiny radars that can be independently aimed in different directions). This is similar to the AESA radar used on the American JSTARS aircraft a system that could locate vehicles moving on the ground. The Swedish AESA is cheaper, because it's built like a long bar, mounted on top of the aircraft. This means the radar can only see, in a 120 degree arc, off both sides of the aircraft. A 60 degree arc in the front and back is uncovered. The radar can spot large aircraft out to nearly 500 kilometers, and more common fighter sized aircraft at about 300 kilometers.
The UAE uses these aircraft to manage air campaigns, including the one under way in Yemen since March 2015. The primary use for UAE AEW aircraft is a war with Iran.